f Numerical Taxonomy of Red-pigmented Bacteria Isolated from a Lowland River, with the Description of a New Taxon, Rugamonas rubra gen. nov., sp. nov.

Summary: Twenty red-pigmented bacterial strains, isolated from river water, and 15 named reference cultures were analysed using numerical taxonomic procedures. A simplified dendrogram, based on the simple matching coefficient and unweighted average linkage clustering algorithm, showed that the environmental isolates were recovered in two phenetic groups, defined at or above the 89% similarity level. Nine strains were contained in phenon 1, which exhibited the general characteristics of the Pseudomonadaceae, but did not match the descriptions of any of the existing genera within this family. A new genus and species, Rugamonas rubra, is proposed for these isolates. The 11 red-pigmented environmental strains in phenon 2 were identified as Serratia rubidaea. The red pigment of R. rubra contains at least two compounds related to prodigiosin. The major component produced a mass spectrum compatible with its being 6-methoxy-2-methyl-3-heptylprodigeosene (m/e 351). A second component produced a mass spectrum indistinguishable from that of prodigiosin itself (m/e 323).